Presently, there is developed a technology of stereophonically reproducing a musical piece downloaded or stored in a memory card. For example, such technology is described in Japanese Patent Laid-open (Kokai) No. 2002-118642.
However, the above-mentioned prior art only supports the monaural call speech and does not sufficiently examine a realistic telephone call using stereo sound. Particularly, full consideration is not given to realistic conversation using a video telephone or the like.